/*
 * Copyright 2009 Mike Cumings
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.kenai.jbosh;

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * A request and response pair representing a single exchange with a remote
 * content manager. This is primarily a container class intended to maintain the
 * relationship between the request and response but allows the response to be
 * added after the fact.
 */
final class HTTPExchange {

	/**
	 * Logger.
	 */
	private static final Logger LOG = Logger.getLogger(HTTPExchange.class
			.getName());

	/**
	 * Request body.
	 */
	private final AbstractBody request;

	/**
	 * Lock instance used to protect and provide conditions.
	 */
	private final Lock lock = new ReentrantLock();

	/**
	 * Condition used to signal when the response has been set.
	 */
	private final Condition ready = lock.newCondition();

	/**
	 * HTTPResponse instance.
	 */
	private HTTPResponse response;

	// /////////////////////////////////////////////////////////////////////////
	// Constructor:

	/**
	 * Create a new request/response pair object.
	 * 
	 * @param req
	 *            request message body
	 */
	HTTPExchange(final AbstractBody req) {
		if (req == null) {
			throw (new IllegalArgumentException("Request body cannot be null"));
		}
		request = req;
	}

	// /////////////////////////////////////////////////////////////////////////
	// Package-private methods:

	/**
	 * Get the original request message.
	 * 
	 * @return request message body.
	 */
	AbstractBody getRequest() {
		return request;
	}

	/**
	 * Set the HTTPResponse instance.
	 * 
	 * @return HTTPResponse instance associated with the request.
	 */
	void setHTTPResponse(HTTPResponse resp) {
		lock.lock();
		try {
			if (response != null) {
				throw (new IllegalStateException("HTTPResponse was already set"));
			}
			response = resp;
			ready.signalAll();
		} finally {
			lock.unlock();
		}
	}

	/**
	 * Get the HTTPResponse instance.
	 * 
	 * @return HTTPResponse instance associated with the request.
	 */
	HTTPResponse getHTTPResponse() {
		lock.lock();
		try {
			while (response == null) {
				try {
					ready.await();
				} catch (InterruptedException intx) {
					LOG.log(Level.FINEST, "Interrupted", intx);
				}
			}
			return response;
		} finally {
			lock.unlock();
		}
	}

}
